Dicroceliasis

History

Fact

Explanation

Abdominal discomfort

Dicroceliasis is caused by a trematode called Dicrocoelium dendriticum, the lanceolate fluke. The infection occurs as a result of accidental oral ingestion of ants infected with metacercaria. After ingestion, the metacercariae encysted in the duodenum. Some adults reside in the duodenum and many ascend the biliary tract through the ampulla of Vater. Presence and attachment to the biliary and intestinal mucosa causes an abdominal discomfort or pain in the upper quadrant or the epigastrium. As the parasite is longer and slender, it travels way up more distal parts of the bile ducts. In heavier infections bile ducts and the biliary epithelium may become enlarged which is followed by fibrosis around the ducts. Hence, the abdominal discomfort may be attributed to enlargement of the liver in such instances. [1,2,3,4]

Diarrhea

Watery diarrhea may also develop in some cases. It is usually mild and owing to the localized inflammatory reaction of the intestinal mucosa. Diarrhea is relapsing in some patients. [1,2,3]

Jaundice

This is attributed to the mechanical obstruction of the proximal parts of the biliary tree. But such obstructions are very rare as the parasite can migrate and resides in more distal parts owing to its slender body. [1,2,4]

Complications

Rarely in heavy infections, patients may get liver abscesses, cholecystitis and very rarely cirrhosis. [1,2,3]

At risk population

Dicroceliasis is more common in regions such as Europe, northern Asia, America and northern Africa. The parasite tends to be found in areas that favor the intermediate hosts (snails and sheep), such as fields with dry, chalky and alkaline soils. [1,2,3,4]

Examination

Fact

Explanation

Abdominal tenderness

Tender hepatomegaly is caused by mechanical obstruction of bile ducts in severe infections. Heavy parasite load cause in severe and lasting inflammation around the intrahepatic biliary duct. This results in tender enlargement of the liver. [1,2]

Differential Diagnoses

Fact

Explanation

Fascioliasis

Fasciola hepatica or the sheep liver fluke is a common parasite of sheep and cattle kept on damp pastures in many parts of the world, but is only occasionally found in men. Most cases have been reported from from sheep rearing countries such as South America, Europe and North America. People usually become infected by eating raw watercress or other water plants contaminated with immature parasite larvae. From the ingestion of metacercariae to the appearance of the first symptoms, it may take few days to 3 months. The immature larval flukes migrate through the intestinal wall, the abdominal cavity, and the liver tissue, into the bile ducts, where they develop into mature adult flukes. Symptoms like abdominal pain, dyspepsia and nausea are caused by localized and or generalized toxic and allergic reactions triggered by this migration. In the chronic phase, abdominal pain may be attributed to painful enlargement of the liver secondary to the adult flukes in the bile ducts which cause obstruction, inflammation and hyperplasia of its epithelium (cholangitis and cholecystitis). This abdominal pain is a biliary colic characterized by an intermittent and often severe pain in the epigastrium or right upper quadrant, and at times between the scapula. [1]

Opisthorchiasis

Opisthorchiasis is caused by trematode Opisthorchis felineus and Opisthorchis viverrini. Infection of humans occurs by ingestion of infected fish. After ingestion, the metacercariae encysted in the duodenum. Some adults reside in the duodenum and many ascend the biliary tract through the ampulla of Vater. Presence and attachment to the biliary and intestinal mucosa causes an abdominal discomfort or pain in the upper quadrant or the epigastrium. It is insidious in onset, dull and intermittent in nature. This may accompanied by other nonspecific symptoms such as fever and chills, as well as fatigue, anorexia, nausea and vomiting. The abdominal discomfort may be attributed to enlargement of the liver, and very rarely cholangitis or cholangiocarcinoma which develop as complications. [2]

Viral hepatitis

Viruses are the commonest cause for hepatitis. The viraemia causes the patient to feel unwell with nonspecific symptoms that include nausea, anorexia and a distaste for cigarettes. Many recover at this stage and remain anicteric. After 1 or 2 weeks some patients become jaundiced and symptoms often improve. Persistence of nausea, vomiting or any mental confusion warrants assessment in hospital. As the jaundice deepens, the urine becomes dark and the stools pale owing to intrahepatic cholestasis. The liver is moderately enlarged and the spleen is palpable in about 10% of patients. [3]

Investigations - for Diagnosis

Acute phase is characterized by high degree of eosinophilia. Leukocytosis may occur. [1,2,3]

Liver function tests

Gamma-glutamyl transpeptidase, ALT, alkaline phosphatase may be high in severe disease. [1,2]

Microscopic examination

Microscopic demonstration of eggs in the stool or in duodenal aspirate is the most practical diagnostic method. Eggs of Dicrocoelium dendriticum are operculated and measure 35-45 µm long by 20-30 µm wide. The eggs are thick-shelled and usually dark brown in color. Eggs are fully embryonated when shed in feces. [1,2,3]

Management - Specific Treatments

Fact

Explanation

Praziquantel

Praziquantel as a single dose (25 mg/kg or less) is the current treatment of choice. Frequently occurring side effects are dizziness, headache, and malaise. Approximately 90% of all patients have abdominal pain or cramps with or without nausea and vomiting.
Praziquantel is not approved for treatment of children less than 4 years old. Niclosamide is used in such instances. [1,2,3]